1. Field of the Invention
An aspect of the present invention relates to a pixel and an organic light emitting display device using the pixel, and more particularly to a pixel that compensates deterioration of an organic light emitting diode and an organic light emitting display device using the pixel.
2. Description of the Related Art
Recently, a variety of flat panel displays having reduced weight and volume as compared to cathode ray tubes, have been developed. Typical flat panel displays include a liquid crystal display, a field emission display, a plasma display panel, and an organic light emitting display device, etc.
The organic light emitting display device displays an image, using an organic light emitting diode that produces light by recombining an electrode and a hole. The organic light emitting display device has the advantage that it has high response speed and is driven by low power.
FIG. 1 is a circuit diagram illustrating a pixel of an organic light emitting display device in the related art. Referring to FIG. 1, a pixel 4 of an organic light emitting display device of the related art includes: an organic light emitting diode OLED; and a pixel circuit 2 connected with a data line Dm and a scan line Sn and controlling the organic light emitting diode OLED.
The anode electrode of the organic light emitting diode OLED is connected to the pixel circuit 2 and the cathode electrode is connected to the second power supply ELVSS. The organic light emitting diode produces light with predetermined luminance in response to the current supplied from the pixel circuit 2.
The pixel circuit 2 controls the amount of current supplied to the organic light emitting diode OLED, in response to a data signal supplied to the data line Dm, when a scan signal is supplied to the scan line Sn. For this configuration, the pixel circuit 2 includes: a second transistor connected between a first power supply ELVDD and the organic light emitting diode OLED; a first transistor M1 connected between the second transistor M2, the data line Dm, and the scan line Sn; and a storage capacitor Cst connected between a gate electrode and a first electrode of the second transistor M2.
A gate electrode of the first transistor M1 is connected to the scan line Sn and a first electrode is connected to the data line Dm. Further, a second electrode of the first transistor M1 is connected to one terminal of the storage capacitor Cst. In this configuration, the first electrode is any one of a source electrode and a drain electrode and the second electrode is the other electrode different from the first electrode. For example, when the first electrode is the source electrode, the second electrode is the drain electrode. The first transistor M1 connected to the scan line Sn and the data line Dm is turned on and supplies a data signal, which is supplied through the data line Dm, to the storage capacitor Cst. In this operation, the storage capacitor Cst is charged to a voltage corresponding to the data signal.
The gate electrode of the second transistor M2 is connected to one terminal of the storage capacitor Cst and the first electrode of the second transistor M2 is connected to the first power supply ELVDD and the other terminal of the storage capacitor Cst. Further, the second electrode of the second transistor M2 is connected to the anode of the organic light emitting diode OLED. The second transistor M2 controls the amount of current flowing from the first power supply ELVDD to the second power supply ELVSS through the organic light emitting diode OLED, in response to the voltage value stored in the storage capacitor Cst. In this configuration, the organic light emitting diode OLED emits light corresponding to the amount of current supplied from the second transistor M2.
However, the organic light emitting display device having the above configuration according to the related art has a problem that it cannot display an image with desired luminance, by efficiency change due to the deterioration of the organic light emitting diode. In other words, as time passes, the organic light emitting diode is deteriorated and accordingly it is not possible to display an image with a desired luminance.